Update Chart.js

Library considers extra optional attribute in the JSON for line chart dataset-
enabled:true/false (default - true).
If set to false, the dataset won't be plotted.
Suitable for switching the visibility of specific datasets.

The next change reduces the number of plotted points by ignoring the points with the same value as their neighbours (e.g. 12,5,5,5,14,14,1,1,1,1,1,2 will plot: 12,5,5,14,14,1,1,2) - useful if the dataset is huge.
TBD: find a proper name for this function and make it optional.